apparmor: refcount the pdb

With the move to permission tables the dfa is no longer a stand
alone entity when used, needing a minimum of a permission table.
However it still could be shared among different pdbs each using
a different permission table.

Instead of duping the permission table when sharing a pdb, add a
refcount to the pdb so it can be easily shared.

Reviewed-by: Georgia Garcia <georgia.garcia@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>

1 files changed, 63 insertions, 0 deletions

diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 9e31a932a644..bcfe8b9cb4c1 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -1887,6 +1887,69 @@ static int __init apparmor_nf_ip_init(void)
 __initcall(apparmor_nf_ip_init);
 #endif
 
+static char nulldfa_src[] = {
+	#include "nulldfa.in"
+};
+struct aa_dfa *nulldfa;
+
+static char stacksplitdfa_src[] = {
+	#include "stacksplitdfa.in"
+};
+struct aa_dfa *stacksplitdfa;
+struct aa_policydb *nullpdb;
+
+static int __init aa_setup_dfa_engine(void)
+{
+	int error = -ENOMEM;
+
+	nullpdb = aa_alloc_pdb(GFP_KERNEL);
+	if (!nullpdb)
+		return -ENOMEM;
+
+	nulldfa = aa_dfa_unpack(nulldfa_src, sizeof(nulldfa_src),
+			    TO_ACCEPT1_FLAG(YYTD_DATA32) |
+			    TO_ACCEPT2_FLAG(YYTD_DATA32));
+	if (IS_ERR(nulldfa)) {
+		error = PTR_ERR(nulldfa);
+		goto fail;
+	}
+	nullpdb->dfa = aa_get_dfa(nulldfa);
+	nullpdb->perms = kcalloc(2, sizeof(struct aa_perms), GFP_KERNEL);
+	if (!nullpdb->perms)
+		goto fail;
+	nullpdb->size = 2;
+
+	stacksplitdfa = aa_dfa_unpack(stacksplitdfa_src,
+				      sizeof(stacksplitdfa_src),
+				      TO_ACCEPT1_FLAG(YYTD_DATA32) |
+				      TO_ACCEPT2_FLAG(YYTD_DATA32));
+	if (IS_ERR(stacksplitdfa)) {
+		error = PTR_ERR(stacksplitdfa);
+		goto fail;
+	}
+
+	return 0;
+
+fail:
+	aa_put_pdb(nullpdb);
+	aa_put_dfa(nulldfa);
+	nullpdb = NULL;
+	nulldfa = NULL;
+	stacksplitdfa = NULL;
+
+	return error;
+}
+
+static void __init aa_teardown_dfa_engine(void)
+{
+	aa_put_dfa(stacksplitdfa);
+	aa_put_dfa(nulldfa);
+	aa_put_pdb(nullpdb);
+	nullpdb = NULL;
+	stacksplitdfa = NULL;
+	nulldfa = NULL;
+}
+
 static int __init apparmor_init(void)
 {
 	int error;